All Questions
Tagged with cryptography computational-number-theory
11 questions
4
votes
0
answers
143
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Road map for learning about the computational/general theory of modular curves/isogenies of abelian varieties for cryptography
I am a graduate math/crypto student. So I've had some free time last year and I heard about elliptic curves in cryptography and how a resilient cryptosystem got demolished by a spectacular attack ...
- 6,377
1
vote
1
answer
185
views
Deduce kernel of isogeny from action on torsion points
I'm stuck with the following problem:
In Petit's work "Faster Algorithms for Isogeny Problems using Torsion Point Images", p. 8, he says that we can deduce $\ker \psi_{N_2}$ knowing the ...
- 12.9k
4
votes
1
answer
363
views
What is meant by a meet-in-the-middle approach?
I'm studing C. Petit's work "Faster algorithms for isogeny problems using torsion point images" (link) and he talks about meet-in-the-middle approach/strategy for solve some isogenies ...
- 188k
4
votes
0
answers
137
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Lattice reduction of basis with non-integer coefficients
Suppose I have an ordered basis $\{b_1, \dots, b_n\}$ of a lattice in $\mathbb{R}^n$, but I do not assume that $b_i \in \mathbb{Z}^n$ for all $1 \leq i \leq n$.
I would like to perform lattice ...
- 554
2
votes
1
answer
172
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On roots of irreducible quadratics modulo composites
Assume factorization of $N$ is unknown. What is the best complexity we know to find roots of the irreducible equation $$ax^2+bx+c\equiv0\bmod N?$$
Is this problem equivalent to any hardness results?
- 13.9k
4
votes
1
answer
309
views
Discrete logarithms and primitive elements in finite fields
The recent papers:
R. Granger, T. Kleinjung, J. Zumbragel, "On the Discrete Logarithm
Problem in Finite Fields of Fixed Characteristic," Trans. Amer. Math.
Soc., 370(5) (2018), 3129–3145.
T....
- 10.4k
3
votes
1
answer
137
views
Subexponential algorithms that apply only one of factoring and discrete logarithm?
Shor (quantum polynomial), Number Field Sieve (subexponential), Pollard rho (square root) all have both factoring and discrete logarithm over $\mathbb F_p^*$ variants.
What are the subexponential ...
- 879
4
votes
1
answer
288
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Is total degree version and $x,y$ degree version of Coppersmith's theorem correct?
The notes here https://web.eecs.umich.edu/~cpeikert/lic13/lec04.pdf have the note 'Small decryption exponent $d$: so far the best known attack recovers $d$ if it is less than $N^{.292}$. This uses a ...
- 218
1
vote
1
answer
138
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How to compute the Müller modular polynomials?
According to R.A.Kazmi's dissertation "Isogenies and Cryptography" (Page 22), given an isogeny degree $l$, the Müller modular polynomials are defined as
$$G_l(x,y)=\sum_{r=0}^{l+1}\sum_{k=0}^{v}a_{...
- 5,407
3
votes
1
answer
383
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Equivalence between Diffie Hellman and Discrete Log
For which non-trivial groups, do we know that the Diffie Hellman problem and the Discrete Log are equivalent?
Is there any group for which we suspect them to be different?
Could there be a finite ...
- 25.4k
2
votes
1
answer
204
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Is there a security analysis of the GQ digital signature scheme?
I'm doing summer cryptography research and I am have been looking for a security analysis of the Guillou-Quisquater (GQ) digital signature scheme, but I have been unable to find one.
Since this is not ...
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